The present invention refers to a novel device for monitoring motion, particularly ballooning motion, of a thread or yarn travelling on a textile machine, the device comprising sensing means producing an electrical sensing signal when contacted by the travelling yarn. The invention also relates to electronic circuitry for processing said electrical sensing signal.
Swiss Pat. No. 457,228 discloses an electronic yarn monitor mounted at a winding machine wherein the travelling yarn performs a traversing motion, and a sensor is arranged in the traversing area. The embodiments of this patent comprise optical and capacitive sensors. Further there is stated that several sensors may be located in the traversing area. The travelling yarn due to the traversing motion produces an A.C. voltage which disappears upon yarn break or standstill and thus is indicative of yarn motion.
Swiss Pat. No. 583,656 and the corresponding U.S. Pat. No. 4,027,232 discloses dynamoelectrical sensing devices adapted for monitoring the motion of oblong or extended objects, such as threads or yarns. Most of these known sensing devices are designed as hollow cylindrical structures comprising at least one insulating guide body, ground and signal electrodes, and a yarn passageway. The ground and signal electrodes extend over the entire circumference of the insulating guide body. The formation of the sensing signal is based on the effect that high frequency electrical signals having noise character are produced by the friction occurring between travelling thread and insulating guide body. The high frequency electrical signals are inductively transferred to the signal electrode which need not be in contact with the travelling thread.